Copper-base alloy



Patented June 12, 1934 PATET FFICE COPPER-BASE Annoy Donald K. Crampton,

Marion, and Henry L.

Burghofl, Yalesville, (20m, assignors to The Chase Companies, Incorporated, Waterbury,

Conn, a corporation No Drawing. Application February Serial No; 655,085

'1 Claim.

This invention relates to alloys composed mainly of copper, silicon and zinc, with or without the addition of aluminum and/or lead.

One object of the invention is to provide copperbase alloys of improved characteristics.

The foregoing and other objects and advantages will appear from the following description and appended claim.

We have discovered that certain alloys composed mainly of copper with a comparatively small percentage of silicon and a still smaller percentage of zinc possess a valuable combination of a number of desirable properties, and also possess certain desirable properties to an exceptionally desirable degree.

We have also discovered that the addition to our copper-silicon-zinc alloys of a smaller percentage of aluminum than silicon, improves their hotworking properties without substantial detriment to the other qualities.

We have further discovered that'the addition of a small percentage of lead to our copper-sili con-zinc and copper-silicon-zinc-aluminum alloys improves their machinability characteristics without serious detriment to the hot and cold working and other properties.

Although we do not intend to limit ourselves to the precise percentages given, alloys contain= ing approximately from 1%% to 3 A;% silicon, from to 1%% zinc, and the balance copper, possess exceptional properties, as will be more fully hereinafter explained. 'An alloy containing approximately 2%% silicon, 1% zinc and the balance copper, constitutes an exceptionally desirable alloy, and will be referred to herein as our preferred high-strength copper-silicon-zinc alloy. An alloy containing approximately 1%% silicon, zinc and the balance copper, constitutes a highly desirable alloy of lesser strength than the foregoing alloy but in which the decreased strength is compensated for, for certain uses, by a gain in ductility and workability, the term workability-including all fabricating operations, such as rolling, drawing, machining, etc.

The addition of approximately from to l of aluminum to our copper-silicon--zinc alloys, preferably with the silicon content reduced in between approximately 1%,% and 2%%, improves their hot-working properties without substantial detriment to the other qualities. preferred high-strength aluminum-containing alloy contains approximately 2 silicon, 1 zinc, 1% aluminum and the balance copper. An alloy containing approximately 1 /z% silicon, zinc, aluminum and the balance copper,

Our-

constitutes a very desirable alloy of lesser strength than the preceding alloy but in which the decreased strength is compensated for, for certain uses, by a gain in ductility and workability.

The addition of approximately from to 1 4% of lead to the foregoing copper-siliconzinc and copper-silicon-zinc-aluminum v alloys improves their machinability without serious detriment to the hot and cold workingand other properties.

Most copper-silicon alloys when molten are quite fluid, but when cast in chill molds for subsequent hot or cold working show poor shrinkage characteristics and are strongly inclined to be very gassy. Various third and fourth constituents have been added to copper-silicon alloys for purposes of improved workability or improved physical properties, but such have usually not improved the casting characteristics; in fact, the more workable an d useful of such alloys seem rather to aggravate the obj ectionable poor shrinkage and gassing features. In addition, some third elements introduce an additional troublesome factor, in that such alloys usually have a layer of liquid slag on the molten metal which is diflicult to entirely separate from the metal during pouring from the ordinary furnaces used in the industry. We have found that small percentages of zinc added to copper-silicon alloys improve the tendency of the castings to show gas holes and improve the shrinkage characteristics. No slag is noted on such alloys and, due to these improvements,it is decidedly easier to obtain clean, sound castings for fabrication than with other coppersilicon alloys.

We have also found that our copper-siliconzinc alloys have excellent hot and cold working properties. By hot working properties we here mean the ability to withstand considerable forging, hot rolling, extrusion, or other'common hot processes without showing brittleness and with relatively low consumption of power. In particular, we have noted that these alloys will with stand severe hot rolling with no tendency towards surface or edge cracks. Further, we have found that in hot extrusion of-rods less power is re-, quired than with some other copper-silicon alloys. Forging tests also indicate less tendency to crack, under severe deformation than other copper alloys of the same general silicon content.

A tensile test on a typical rod of our preferred high-strength copper-silicon-zinc alloy 1 /2" in diameter, drawn cold without intermediate annealing from 2%" diameter, showed the following properties:

91,400 lbs. per sq. in. maximum strength 41% elongation in 2 inches 67% contraction of area It will be seen from the preceding figures that our preferred alloy possesses a remarkable combination of high strength, elongation and contraction of area at fracture on tensile test.

A sample rod of our foregoing alloy, drawn to spring temper wire, showed a strength on tensile test of 156,000 per square inch with, 4% elongation in two inches. Not only is this a remarkable tensile strength for a copper-base alloy, but it will be seen from the 4%;% elongation that the wire is free from brittleness.

- A sample rod of our same alloy, inch diameter and in annealed condition showed on tensile test a contractionfof area at fracture of 82%.

A rod of the same alloy cold drawn without any intermediate annealing to a total area reduction of 93% of the original area, still showed a contraction of area at fracture, on tensile test, of 38%, indicating extreme toughness and considerable capacity for further cold working without annealing.

. The fatigue-endurance limit of our alloys are better than those of most other copper alloys. Such tests, carried out on spring temper sheet 0.032" thick made of'our same alloy, showed an endurance limit of 30,500 lbs. per square inch, which is exceptionally high for a copper alloy also possessing good casting and working properties and low cost.

Alloys made in accordance with our invention possess an excellent combination of strength and ductility, can be produced at low cost, and possess excellent corrosion resistance, particularly to saline water, the atmosphere, and dilute acids.

Our invention contemplates alloys of the nature, and possessing the characteristic properties, herein set forth, whether or not one or more additional metals are present.

' We claim:

An alloy characterized by being resistant to cracking during hot-working, and by being freely hot-workable despite which it also is capable of being givena very high tensile strength by coldworking, and consisting of: 2% per cent to 3 /4 per cent of silicon; a percentage of zinc from to 1 and always less than one-half the percentage of silicon; and the balance being copper and constituting at least 95 per cent of the alloy.

DONALD K. CRAIVIPTON. HENRY L. BURGHOFF. 

